spmi: add a first basic spmi driver for Apple SoC

Signed-off-by: Jean-Francois Bortolotti <jeff@borto.fr>

Author: Jean-Francois Bortolotti

drivers/spmi/Kconfig

@@ -45,4 +45,12 @@ config SPMI_MTK_PMIF
 	  This is required for communicating with Mediatek PMICs and
 	  other devices that have the SPMI interface.
 
+config SPMI_APPLE
+	tristate "Apple SoC SPMI Controller platform driver"
+	depends on ARCH_APPLE || COMPILE_TEST
+	help
+	  This enables basic support for the SPMI controller present on
+	  many Apple SoCs, including the t8103 (M1) and t600x
+	  (M1 Pro/Max).
+
 endif

drivers/spmi/Makefile

@@ -7,3 +7,4 @@ obj-$(CONFIG_SPMI)	+= spmi.o spmi-devres.o
 obj-$(CONFIG_SPMI_HISI3670)	+= hisi-spmi-controller.o
 obj-$(CONFIG_SPMI_MSM_PMIC_ARB)	+= spmi-pmic-arb.o
 obj-$(CONFIG_SPMI_MTK_PMIF)	+= spmi-mtk-pmif.o
+obj-$(CONFIG_SPMI_APPLE)	+= spmi-apple-controller.o

drivers/spmi/spmi-apple-controller.c

@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Apple SoC SPMI device driver
+ *
+ * Copyright The Asahi Linux Contributors
+ *
+ * Inspired by:
+ *		OpenBSD support Copyright (c) 2021 Mark Kettenis <kettenis@openbsd.org>
+ *		Correllium support Copyright (C) 2021 Corellium LLC
+ *		hisi-spmi-controller.c
+ *		spmi-pmic-ard.c Copyright (c) 2021, The Linux Foundation.
+ */
+
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/spmi.h>
+
+/* SPMI Controller Registers */
+#define SPMI_STATUS_REG 0
+#define SPMI_CMD_REG 0x4
+#define SPMI_RSP_REG 0x8
+
+#define SPMI_RX_FIFO_EMPTY BIT(24)
+#define SPMI_TX_FIFO_EMPTY BIT(8)
+
+/* Apple SPMI controler */
+struct apple_spmi {
+	void __iomem *regs;
+	struct spmi_controller *ctrl;
+};
+
+static inline u32 read_reg(struct apple_spmi *spmi, int offset)
+{
+	return (readl_relaxed(spmi->regs + offset));
+}
+
+static inline void write_reg(u32 value, struct apple_spmi *spmi, int offset)
+{
+	writel_relaxed(value, spmi->regs + offset);
+}
+
+static int spmi_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 slave_id,
+			 u16 slave_addr, u8 *__buf, size_t bc)
+{
+	struct apple_spmi *spmi;
+	u32 spmi_cmd = opc | slave_id << 8 | slave_addr << 16 | (bc - 1) |
+		       (1 << 15);
+	u32 rsp;
+	volatile u32 status;
+	size_t len_to_read;
+	u8 i;
+
+	spmi = spmi_controller_get_drvdata(ctrl);
+
+	write_reg(spmi_cmd, spmi, SPMI_CMD_REG);
+
+	/* Wait for Rx FIFO to have something */
+	/* Quite ugly msleep, need to find a better way to do it */
+	i = 0;
+	do {
+		status = read_reg(spmi, SPMI_STATUS_REG);
+		msleep(10);
+		i += 1;
+	} while ((status & SPMI_RX_FIFO_EMPTY) && i < 5);
+
+	if (i >= 5) {
+		dev_err(&ctrl->dev,
+			"spmi_read_cmd:took to long to get the status");
+		return -1;
+	}
+
+	/* Read SPMI reply status */
+	rsp = read_reg(spmi, SPMI_RSP_REG);
+
+	len_to_read = 0;
+	/* Read SPMI data reply */
+	while (!(status & SPMI_RX_FIFO_EMPTY) && (len_to_read < bc)) {
+		rsp = read_reg(spmi, SPMI_RSP_REG);
+		i = 0;
+		while ((len_to_read < bc) && (i < 4)) {
+			__buf[len_to_read++] = ((0xff << (8 * i)) & rsp) >>
+					       (8 * i);
+			i += 1;
+		}
+	}
+
+	return 0;
+}
+
+static int spmi_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 slave_id,
+			  u16 slave_addr, const u8 *__buf, size_t bc)
+{
+	struct apple_spmi *spmi;
+	u32 spmi_cmd = opc | slave_id << 8 | slave_addr << 16 | (bc - 1) |
+		       (1 << 15);
+	volatile u32 rsp;
+	volatile u32 status;
+	size_t i = 0, j;
+
+	spmi = spmi_controller_get_drvdata(ctrl);
+
+	write_reg(spmi_cmd, spmi, SPMI_CMD_REG);
+
+	while (i < bc) {
+		j = 0;
+		spmi_cmd = 0;
+		while ((j < 4) & (i < bc)) {
+			spmi_cmd |= __buf[i++] << (j++ * 8);
+		}
+		write_reg(spmi_cmd, spmi, SPMI_CMD_REG);
+	}
+
+	/* Wait for Rx FIFO to have something */
+	/* Quite ugly msleep, need to find a better way to do it */
+	i = 0;
+	do {
+		status = read_reg(spmi, SPMI_STATUS_REG);
+		msleep(10);
+		i += 1;
+	} while ((status & SPMI_RX_FIFO_EMPTY) && i < 5);
+
+	if (i >= 5) {
+		dev_err(&ctrl->dev,
+			"spmi_write_cmd:took to long to get the status");
+		return -1;
+	}
+
+	rsp = read_reg(spmi, SPMI_RSP_REG);
+	(void)rsp; // TODO: check stuff here
+
+	return 0;
+}
+
+static int spmi_controller_probe(struct platform_device *pdev)
+{
+	struct apple_spmi *spmi;
+	struct spmi_controller *ctrl;
+	int ret;
+
+	ctrl = spmi_controller_alloc(&pdev->dev, sizeof(struct apple_spmi));
+	if (IS_ERR(ctrl)) {
+		dev_err_probe(&pdev->dev, PTR_ERR(ctrl),
+			      "Can't allocate spmi_controller data\n");
+		return -ENOMEM;
+	}
+
+	spmi = spmi_controller_get_drvdata(ctrl);
+	spmi->ctrl = ctrl;
+	platform_set_drvdata(pdev, ctrl);
+
+	spmi->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(spmi->regs)) {
+		dev_err_probe(&pdev->dev, PTR_ERR(spmi->regs),
+			      "Can't get ioremap regs.\n");
+		return PTR_ERR(spmi->regs);
+	}
+
+	ctrl->dev.of_node = of_node_get(pdev->dev.of_node);
+
+	/* Callbacks */
+	ctrl->read_cmd = spmi_read_cmd;
+	ctrl->write_cmd = spmi_write_cmd;
+
+	ret = spmi_controller_add(ctrl);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"spmi_controller_add failed with error %d!\n", ret);
+		goto err_put_controller;
+	}
+
+	/* Let's look for other nodes in device tree like the rtc */
+	ret = devm_of_platform_populate(&pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"spmi_controller_probe: devm_of_platform_populate failed with error %d!\n",
+			ret);
+		goto err_devm_of_platform_populate;
+	}
+
+	return 0;
+
+err_put_controller:
+	spmi_controller_put(ctrl);
+err_devm_of_platform_populate:
+	return ret;
+}
+
+static void spmi_del_controller(struct platform_device *pdev)
+{
+	struct spmi_controller *ctrl = platform_get_drvdata(pdev);
+
+	spmi_controller_remove(ctrl);
+	spmi_controller_put(ctrl);
+}
+
+static const struct of_device_id spmi_controller_match_table[] = {
+	{
+		.compatible = "apple,spmi",
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, spmi_controller_match_table);
+
+static struct platform_driver spmi_controller_driver = {
+	.probe		= spmi_controller_probe,
+	.remove		= spmi_del_controller,
+	.driver		= {
+		.name	= "apple-spmi",
+		.owner	= THIS_MODULE,
+		.of_match_table = spmi_controller_match_table,
+	},
+};
+module_platform_driver(spmi_controller_driver);
+
+MODULE_AUTHOR("Jean-Francois Bortolotti <jeff@borto.fr>");
+MODULE_DESCRIPTION("Apple SoC SPMI driver");
+MODULE_LICENSE("GPL");